A long standing problem related to sources of illumination in public places is prevention of, or at least resistance to, tampering or vandalizing, particularly when the source is publicly accessible. Examples include light fixtures in elevators, hallways, train or bus passenger compartments, etc. The long standing nature of this problem is evidenced by U.S. Pat. No. 940,899 issued to W. G. Sherrer in 1909 for a safety globe and guard for a gas lamp, intended to thwart “mischievous persons [from] . . . reaching the light.” The guard for restricting access to the gas burner is a wire frame globe with a tamper resistant lock box (15).
The tamper proofing problem applies to many types of fixtures or devices that may be used in public places, for example: smoke detectors, thermostats, exit signs, alarms, speakers, etc. Because of their long history, light sources are used as a representative device in the present consideration of prior art.
In most situations requiring tamper resistance, the light source is a fixture, or at least a socket, that is mounted on, or recessed within a wall or ceiling surface. A known method for providing tamper resistance includes mounting a light source/fixture on or within the mounting surface, covering it with a breakage resistant transparent or translucent shield (e.g., Lexan®), and only allowing access to the light source and/or fixture from behind the mounting surface. For example, this method is used in prison cells as disclosed in U.S. Pat. No. 4,453,202 (Morris et al.; 1984) wherein a vandal-resistant light fixture (11) has a transparent cover (19) attached to a mounting surface (wall 16) by threaded studs (13) extending rearward from the cover through the wall to be attached with nuts (15) on the other (rear) side of the wall, i.e., in an area outside of the chamber being lighted. A light source (12) is removably attached inside the cover by means of an access hole (83) through the wall.
It is apparent that the forgoing example of tamper resistance results from an inability to detach the cover or the covered fixture from the lighted side of the mounting surface (wall) unless accessed from the rear of the surface. Also, the light source is inaccessible from the lighted side of the surface but can be removed from the rear (through the access hole) without removing the cover. In most situations, this method of tamper resistance is inconvenient at best, and usually is not even possible. Other examples of fixtures that are accessible from the front or outside of the mounting surface can be seen in U.S. Pat. No. 1,357,539 (Bissell; 1920) and U.S. Pat. No. 4,344,114 (Denhart; 1982) wherein a shielding means comprising bars (6 in Bissell) or a housing (H in Denhart) with see-through tamper-proof panels (52, 54, 56); is held closed by a padlock (e.g., 64 in Denhart).
Although relatively secure, use of a padlock is both unsightly and expensive; and secure rear access to a fixture is often unpractical. It is an object of the present invention to overcome these and other limitations of the prior art to provide an inexpensive and practical tamper resistant fixture enclosure. It is a further object to extend the principles of the present invention to apply to fixtures or devices that may be rugged enough that they do not require an added enclosure, but which require tamper resistant attachment to a mounting surface.